Showing papers by "Eindhoven University of Technology published in 1977"
TL;DR: In this paper, the dehydration at 95° of d-fructose (0.25 m -1.0 m ) to 5-hydroxymethyl-2-furaldehyde (HMF) and the rehydration of HMF (0,25-1.5 m) to levulinic and formic acids in 0.5-2 m HCl has been studied.
159 citations
TL;DR: A review of the basic theory on thermally stimulated luminescence (TSL) and conductivity (TSC) based on a certain simple model is given in this article, where approximate analytical expressions for the shapes of the TSL and TSC curves are derived.
138 citations
TL;DR: In this article, the authors measured the particle dimensions in blends of low density polyethylene (PE) and polystyrene (PS) made by mixing in the molten state and have been shown to depend on the viscosity of the mixed system.
125 citations
TL;DR: In this article, the influence of pH (1 − 6) on the rates and yields in the dehydration of d -fructose to 5-hydroxymethyl-2-furaldehyde (HMF) and the rehydration of HMF to levulinic and formic acids at 175° has been studied by using a stirred tank-reactor.
123 citations
TL;DR: In this article, the influence of water concentration on the rates and yields in the dehydration of d -fructose to 5-hydroxymethyl-2-furaldehyde (HMF) and in the rehydration of HMF to levulinic and formic acids at 95° has been studied by the addition of polyethylene glycol-600 (PG-600) to the reaction mixtures.
95 citations
TL;DR: In this paper, the authors investigated the mechanism of the chlorine evolution on titanium electrodes coated with a layer of ruthenium oxide and titanium oxide under different experimental conditions, and on a RUThenium electrode, both in acidic chloride solution, has been investigated.
73 citations
TL;DR: In this article, the product distribution (determined by isotachophoresis and ion-exchange chromatography) was determined at pH 8-11 and 45-65.
68 citations
TL;DR: The extraction and subsequent liquid chromatographic analysis of human plasma samples for cortisol is described, resulting in a recovery for cortisol of 96% and a detection limit of 1 microgram cortisol in 100 ml plasma.
59 citations
TL;DR: A new bifunctional catalyst of cobalt-phthalocyanine (CoPc) has been developed in which an efficient cooperation between oxidation catalyst and basic sites has been attained.
59 citations
TL;DR: A new approach to target chemistry—comprising target preparation, separation of tellurium and carrier-free radioiodine, and target-material recovery—is presented for routine production of sizeable quantities of iodine-123 for medical diagnosis.
57 citations
TL;DR: In this paper, the spectral noise density of the voltage between two arbitrarily shaped and placed sensor electrodes on a conductor was derived for conductivity fluctuations due to 1/f noise by using empirical 1 /f noise relations.
Abstract: A general relation is derived for the spectral noise density of the voltage between two arbitrarily shaped and placed sensor electrodes on a conductor, when a constant current or voltage is applied to another pair of arbitrarily shaped and placed driver electrodes. The general relation is based on the sensitivity calculation in linear electrical networks. The relation is elaborated for conductivity fluctuations due to 1/f noise by using empirical 1/f noise relations. The influence of spot radii of the sensor electrodes on the noise is demonstrated.
TL;DR: Aqueous solutions of the nitrates of aluminum and chromium were investigated with X-ray diffraction at t = 25°C in this paper, where the experimental intensity was interpreted in terms of an electron product function which is a sum of various pair contributions.
TL;DR: In this article, the inelastic and elastic scattering of polarized protons (E = 17.2, 20.4, 24.6 MeV) by 54, 56 Fe and 58, 60, 62 Ni have been investigated.
TL;DR: In this article, a thermogravimetric analysis of yttrium iron garnet, Y3Fe5O12−δ, in the temperature range 950-1270°C is presented.
TL;DR: This paper concerns a general theory of linear optical data-processing systems, well-known basic ideas are critically reviewed, fundamental constraints upon the system behavior are investigated, and a new operational notation is proposed.
Abstract: This paper concerns a general theory of linear optical data-processing systems. Well-known basic ideas are critically reviewed, fundamental constraints upon the system behavior are investigated, and a new operational notation is proposed. Every system is considered as a bidirectional processor and every two-dimensional signal is equivalently described in the space and frequency domain. Without referring to field-theoretical notation, the constraints of “reciprocity” and “losslessness” are introduced. In rough terms, reciprocity states equality of transmissions A → B and B → A, where A and B are points in the two reference planes, losslessness states equality of signal energies in the two planes. “Symmetry” has to be independently defined in the space and the frequency domain, and “shift invariance” and “spreadlessness” appear to be dual constraints. The important constraint of “time reversibility” is obtained when a system simultaneously satifies reciprocity and losslessness. In the second part, the general theory is applied to lenses, sections of free space, Fourier transformers, and magnifiers. With the aid of a suitable shorthand notation, the main results of Fourier optics can be easily derived.
TL;DR: In this paper, the authors treated the phenomenon of partial coherence in the frequency domain, rather than in the time domain, and defined a spectral degree of coherence as a suitably normalized power spectrum.
Abstract: The phenomenon of partial coherence is treated in the frequency domain, rather than in the time domain. The starting-point of the description in the frequency domain is the set of mutual and auto power spectra of N signals, arranged in the form of an N × N Hermitian matrix. The necessary and sufficient condition for a Hermitian matrix to be a matrix of power spectra is that the Hermitian matrix is positive (semi-) definite. Apart from the temporal degree of coherence, which is the normalized coherence function, a spectral degree of coherence is defined as a suitably normalized power spectrum. Due to the positive (semi-) definiteness of the matrix of power spectra, the absolute value of the spectral degree of coherence is bounded by 1. Complete coherence is equivalently defined by ‘rank of the matrix of power spectra equals 1’ and ‘absolute value of the spectral degree of coherence equals 1’. Signals which are coherent in the above sense, seem to emanate from one single point source; furthermore, when prop...
TL;DR: The importance of the inside diameter of the separation compartment of electrophoretic equipment in which tubes are used in achieving optimal stabilization against conventive disturbances and for limiting the temperature increase is demonstrated.
TL;DR: In this article, the electroosmosis of a rod placed in a cylindrical hole drilled in a piece of PTFE is measured, which can be applied to any material from which an appropriate rod can be formed; the method can also be applied also to materials from which only rodlike pieces are available.
TL;DR: The contribution of gas chromatographic retention behavior of methylene group increments and differences in the retention indices (δ I ) of isomers of alkylbenzenes up to C 16 on squalane and acetyltri- n -butyl citrate was studied in this article.
TL;DR: In this article, a number of successive approximation algorithms for the repeated two-person zero-sum game called Markov game using the criterion of total expected discounted rewards were presented, where stopping times are introduced in order to simplify the proofs.
Abstract: This paper presents a number of successive approximation algorithms for the repeated two-person zero-sum game called Markov game using the criterion of total expected discounted rewards. AsWessels [1977] did for Markov decision processes stopping times are introduced in order to simplify the proofs. It is shown that each algorithm provides upper and lower bounds for the value of the game and nearly optimal stationary strategies for both players.
TL;DR: In this article, procedures for the queuing of D-fructose and its dehydration products, S-hydroxymethyI-2W furaldehyde (HMF), Ievulinic acid, and a "humin" were developed.
TL;DR: In this article, a method for the routine preparation of high resolution stabilized phase open tubular (SPOT) columns is described, where a finely dispersed siliceous material is treated with benzyltriphenylphosphoniumchloride and dynamically coated onto the inside wall of glass capillary columns.
Abstract: A method is described for the routine preparation of high resolution stabilized phase open tubular (SPOT) columns. A finely dispersed siliceous material (Cab-O-Sil) is treated with benzyltriphenylphosphoniumchloride and dynamically coated onto the inside wall of glass capillary columns. Additional dynamics coating with a polar stationary phase yields thermostable columns of high efficiency. The columns show favourable adsorption properties and good long term stability. The mechanical stability of the stationary phase film is explained in terms of the rheological behaviour of concentrated disperisons. The designation PLOT columns appers inapplicable, and these columns will be referred to as SPOT columns. A theoretical model, describing band spreading in SPOT columns, is proposed and compared with the experimental results. Some applications in routine use and in ultra trace analysis are presented.
TL;DR: In this article, the relationship between the structures of alkylbenzenes and the temperature and pressure coefficients of their retention indices were studied, in addition to their dependence on the polarity of the stationary phase, the column inlet pressure and the nature of the carrier gas.
TL;DR: In this paper, the optical transmission of powdered single crystals of magnetite was measured in the spectral range from 200 to 4000 at temperatures between 77 and 300 K. The spectrum of pure magnetite shows drastic changes at the Verwey transition, and a small splitting up of the two high-temperature phonon bands is observed.
Abstract: The optical transmission of powdered single crystals of magnetite was measured in the spectral range from 200 to 4000 ${\mathrm{cm}}^{\ensuremath{-}1}$ at temperatures between 77 and 300 K. The measurements are compared with those on Ti-substituted magnetite. The spectrum of pure magnetite shows drastic changes at the Verwey transition. In the low-temperature phase, a small splitting up of the two high-temperature phonon bands is observed.
TL;DR: In this article, the authors measured the Barkhausen noise spectra on thin uniaxial 83-17 Ni−Fe films and compared these spectra with the known magnetic behaviour of these films.
Abstract: In this paper Barkhausen noise spectra are shown that were measured on thin uniaxial 83-17 Ni−Fe films and these spectra were compared with the known magnetic behaviour of these films. On these types of sample the Barkhausen effect had been investigated by Lambeck [1], but their Barkhausen noise spectra have not been investigated so far. The film thicknessd m in our experiments ranged between 400 and 2400 A. In this range a change occurs in the dynamics of the magnetization behaviour caused by transitions of the type of domain wall. The results presented here show the very strong dependence of the Barkhausen noise spectra on the type of domain wall. Films with Bloch walls always show a frequency dependence off −1.7 in the higher frequency range. Samples in the thickness range where the transition occurs from the Neel wall via the cross-tie wall to the Bloch wall, have exponents between −1 and −2. The frequencyf c above which the measured noise intensity begins to decrease varies very much for the different films. The curve off c versus film thicknessd m has the same form as the curve of the domain wall mobilitym versusd m.
TL;DR: A submitted manuscript is the version of the article upon submission and before peer-review as mentioned in this paper, while a published version is the final layout of the paper including the volume, issue and page numbers.
Abstract: • A submitted manuscript is the version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers.
TL;DR: Magnetostriction measurements on mixed crystals Fe3-,Tiz04 were reported for the temperature range of 77 to 300 K as mentioned in this paper, and the magnetostriction constants 2.1 and 2100 increase strongly by the presence of tetrahedral Fez' ions.
Abstract: Magnetostriction measurements on mixed crystals Fe3-,Tiz04 are reported for the temperature range of 77 to 300 K. The magnctostriction constants 2.1 and 2100 increase strongly by the presence of tetrahedral Fez' ions. The uncertainty about the valency distribution in the mixed crystals interfered wit11 the explanation of the composition dependence of the magnetostriction. The magnetostriction data do not exclude the presence of tetrahedral Fe2+ for the compositions x < 0.5.
TL;DR: In this article, the relationship between the structure and retention indices of alkylbenzenes on three stationary phases with different polarities and Δ I values was studied and the extent to which Δ I can be used for identification purposes on the basis of comparisons between measured retention data and tabulated data and/or calculated data based on retention index increments corresponding to characteristic functional groups in the molecules.